Hmmmmmm

Scientists Track Down Source of Earth’s Hum | Wired Science | Wired.com: "After discovering the mysterious low-frequency buzz in 1998, scientists figured out that the Earth’s hum is caused not by earthquakes or atmospheric turbulence, but by ocean waves colliding with the seafloor. Now, researchers have pinpointed the source of the Earth’s “background noise,” and it looks like it’s coming primarily from the Pacific coast of North America."